1. Field of the Invention
The present invention relates to an image recording and reproducing device, the method and a memory medium readable with computer, which are preferably used for recording and reproducing electronic watermark and image data.
2. Related Background Art
Currently, communication technology for various data such as image data utilizing the internet has been rapidly developed and increasingly used. Further, digital satellite broadcasting has been started and digital AV instruments such as DVD and the like have become widespread. Therefore, digitization of image, music etc., is increased and the softwares commercially available to users are mainly based on digital data.
Such digital data images, music softwares and the like can be easily copied and edited by the use of a personal computer. Further, it is also possible to send or communicate unfairly copied data to a unspecified number of the general individuals on the internet. Thus such wide spreading of digital works has arisen new problems from the viewpoints of the piracy and the unfair copy.
The above-mentioned problems were conventionally avoided by jointly using encryption of data, scramble technology or the like, and the penalty system or the like, as a technology for the unfair copy or a security technology on the internet. Alternatively, the unfair copy was prevented by the macrovision system for the software of picture and the CGMS system based on copy generation information. However, these copyright protection technology have both advantages and disadvantages, and no perfect copyright protection technology has been established.
Thus, as the technology of preventing and suppressing the unfair copy, the electronic watermark technology was considered. In this watermark technology, on ID information or information intended by a manufactures are buried in digital works as electronic watermark information which is different to visually recognize with the human eye and is carried while being hidden therein. The watermark effect is realized by burying the watermark information in redundant data portions as a kind of noise. Alternatively, it is also possible to further increase the watermark effect by burying the watermark information in main data portions as well as the redundant data portions.
When this electronic watermark information is used in image data, the buried watermark information is not completely removed even by the data compressing and the file processing, and the watermark information can be continuously held in the image data. As the result unauthorized copying can be prevented.
When the electronic watermarks in the prior art example are used in for example, image data, watermark data is buried in the redundant image portions and the main data portions as noise. Therefore, in the prior art, deterioration of the quality of image is larger than in a case where no electronic watermarks are introduced. However, in order to prevent the deterioration of image quality as much as possible, if a smaller amount of the electronic watermark data is buried in image data, the watermark data can be erased by the file processing. Further, if the master image record and the electronic watermark data were simultaneously buried in image data, the watermark data cannot be separated from the entire data and deteriorated images are recorded.